GNU `tar' saves many files together into a single tape or disk archive, and can restore individual files from the archive. It includes multivolume support, the ability to archive sparse files, automatic archive compression/decompression, remote archives and special features that allow `tar' to be used for incremental and full backups. It also includes `rmt', the remote tape server (the `mt' tape drive control program is in GNU `cpio').
GNU Radius is a RADIUS server and an accompanying set of monitoring utilities. It features MySQL and PostgreSQL interfaces for authentication and/or logging (the ODBC interface allows you to use almost any existing DBMS for that purpose), the ability to rewrite RADIUS requests from various NASs to normalize them to a more understandable format, and the ability to completely customize the behavior of RADIUS authentication and accounting based on NAS and user attributes.
GNU Anubis is an SMTP message submission daemon. It represents an intermediate layer between the mail user agent (MUA) and mail transport agent (MTA), receiving messages from the MUA, applying to them a set of predefined changes, and finally inserting modified messages into an MTA routing network. The set of changes applied to a message is configurable on a system-wide and per-user basis. The built-in configuration language used for defining sets of changes allows for considerable flexibility and is easily extensible.
GNU Mailutils is a rich and powerful protocol-independent mail framework. It contains a series of useful mail libraries, clients, and servers. These are the primary mail utilities for the GNU system. The central library is capable of handling electronic mail in various mailbox formats and protocols, both local and remote. Specifically, this project contains a POP3 server, an IMAP4 server, and a Sieve mail filter. It also provides a POSIX "mailx" client and a collection of other handy tools.
libposix is an impementation of the core functionality of all Unix systems. It is a full, cross-platform implementation of the POSIX 2008 standard. It is meant to replace existing implementations of a Unix system's core libraries. It is an exact implementation of POSIX 2008 and nothing else (no extensions, no previous POSIX versions). However, it works well with possible extensions to the core system functionallity (for example, GNU or BSD).
Ductus is a wiki system designed to handle arbitrarily-structured content and a variety of workflows. With Ductus, programmers can easily define classes of structured content, providing rich mechanisms for user interaction. For instance, the Wikiotics project uses Ductus to allow people to collaborate on "language lessons," which can later be used as quizzes or flashcards. Such modes of interaction are not possible with most wikis, which are designed primarily to handle freely-structured text.
openmamba is a fully featured GNU/Linux distribution for desktops, notebooks, netbooks, and servers. It runs on computers based on the 32-bit Intel x86 architecture, or on 64-bit AMD processors in 32-bit mode. openmamba comes with both free and closed source drivers for the most frequently used video cards. It supports compiz out of the box. It has preinstalled multimedia codecs, and can install the most frequently used closed source applications for GNU/Linux (such as Flash Player or Skype) very easily.